Glow plug



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Patented Oct. 19, 1937 UNITED STATES PATENT OFFICE GLOW PLUG poration ofDelaware Application February 13, 1937, Serial No. 125,539

5 Claims.

My invention relates to igniting devices, commonly referred to as glowplugs, for use with internal combustion engines to ignite thecombustible mixture within the engine cylinder; such 5 plugs beingcommonly used in heavy oil and the like engines at the starting thereof.

, Glow plugs of the type to which my invention relates include anigniting element of high resistance which is heated to ineandescence bya l current of electricity of low voltage, for example from a sourcesupplying current at about two volts or thereabout, and the combustiblemixture comes into direct contact with said igniting element. As stated,such plugs are for use when starting l the engine and the heatingcurrent is ordinarily discontinued after the engine is in operation andhas become heated, after which ignition occurs automatically as inDiesel or semi-Diesel engines.

My invention relates particularly to glow plugs 2'0 wherein current issupplied to the igniting element through two electrodes which extendthrough passages in an insulating member, which is secured in placewithin an opening or passage in a cylinder head or equivalent cylinderwall; and

in which no metallic shell or casing is made use of for supporting theinsulating member whereby the current supply electrodes are insulatedfrom one another. That is neither of the electrodes is grounded to theengine structure, and both are supported and insulated from one anotherby an insulating member which has merely to be secured in place within apassage in the cylinder wall in installing the plug for its intendeduse.

The preferred form oi my invention is illustrated in the drawing whichaccompanies and forms a part of this specification, and the featureswherein the same consists are particularly pointed out in the concludingclaims.

, In the drawing:

Figure 1 is a view showing a section upon a central axial planeextending longitudinally of a glow rplug made in accordance with myinvention, and illustrating the same in place in a passage in a cylinderhead.

Figure 2 is a view showing a section upon a transverse plane indicatedby the line 2-2, Figure 1, looking down.

Figure 3 is a perspective view showing a dished Washer whereby the plugis secured in place, by a suitable gland nut as illustrated in Figure l.

Referring to the drawing, the numeral 5 designetes a cylinder headhaving a passage 6 leading to inside the cylinder, and 1 is acylindrical insulating member made of a ceramic or equivalent insulatingmaterial. This member has two (Cl. 12S-145) passages extendingthroughout its length, and within which passages the electrodes 8, 9 ofthe plug are permanently assembled as shown. These electrodes arecommonly made of copper or like good conducting material. 5

The electrodes are preferably enlarged at their lower or inner ends, asat I0, II, which enlarged ends t within enlarged lower ends of saidpassages as shown; and gas-tight joints between them and the passagesalong which they extend are secured by suitable cement as at I2, I3which surrounds the electrodes at the points where the enlarged lowerends merge with the smaller upper parts thereof; a cement partaking ofthe nature of a glass being preferably used. The numeral I4 designatesthe incandescent igniting element of the plug, the same being preferablyin the form of a coil the ends of which are fastened, as by wel-ding, tothe inner ends of the electrodes. This coil is made from a material ofhigh resistance so that it will be heated to incandescence by a currentof electricity supplied thereto through the electrodes 8, 9.

The passage 6 is formed with an internal ledge, at I5, and theinsulating member l has a lower shoulder which overlies this ledge andwhereby said member is supported inside said passage. Said insulatingmember is reduced in diameter at its upper or outer end, whereby anupper shoulder is provided at I6; and Il designates a gland nut whichscrews into the upper end of the passage 6 and holds the plug in placetherein. This gland nut has a metallic holding ring I8 shown as securedwithin its upper end by an inturned flange 4I9 and through which theupper end of the insulating member 'I extends, so that said holding ringremains permanently assembled with the gland nut; and this holding ringbears upon a slightly dished washer 20 which presses against a softcopper gasket 2I resting upon the ledge I6, whereby the insulatingmember 1 is held in place by slightly yieldable securing means as willbe understood.

The insulating member 1 is provided near its r upper end with oppositelydisposed recesses 22, 23 whereby short lengths of the electrodes 8, 9are exposed, so that supply conductors 25, 26 extending transverse tothe axis of the plug may contact with the sides of said electrodesadjacent their upper ends, as shown particularly in Figure l; andclamping means are provided for forcing said supply conductors againstthe sides of said electrodes to thereby connect them to the plug andsecure good contacts between the conductors and the electrodes.

In the preferred form of my invention illustrated said clamping memberscomprise U-shaped bands 2l, 28 which are supported by and extend aboutand bear against the sides of the upper end of the insulating member,whereby said member serves as an abutment which restrains sidewisemovement of the clamping members which, as will be seen, extend inopposite directions from the axis of the plug. The ends of these bandsare inturned and brought together, as at 29, 39, Fig# ure 2, and haveholes through which screws 3 l, 32 extend; nuts 33, 343 being arrangedbetween the sides of the bands so as to provide better threads for thescrews to cooperate with in forcing the conductors 25, 26 against thesides of the electrodes 8, 9. The inner ends of said screws, which aswill be seen extend at right angles to the electrodes, engage with thecurrent supply conductors 25, 2S and force them against the electrodes,and said bands have oppositely arranged side openings 36, 37throughwhich said conductors extend, as best shown in Figure 2.

Having thus described and explained my invention, I claim and desire tosecure by Letters Patent: -V

l. In a glow plug of the class described, an insulating member adaptedto be held in place within a passage in a cylinder wall, and whichmember has a longitudinally extending passage; an electrode locatedWithin said passage and through which current is supplied to an ignitingelement at the inner end of the plug; a clamping member supported by andlocated adjacent the upper end of said insulating member and engaging alateral part thereof, so that the insulating member provides an abutmentwhich restrains sidewise movement of said clamping member; and a screwcarried by said clamping member and arranged at right angles to saidelectrodes; said insulating member having a recess adjacent the innerend of said screw whereby a short length of said electrode is exposed,and whereby a transversely extending supply conductor may be forced intoengagement with said electrode by the inner end of said screw. Y

2. In a glow plug ofthe class described, an insulating member adaptedtobe held in place within a passage in a cylinder wall, and which memberhas a longitudinally extending passage; an electrode located within saidpassage and through which current is supplied to an igniting element atthe inner end of the plug; a U-clamping member extending about andsupported by and located adjacent the upper end of said insulatingmember whereby said upper end provides an abutment which restrainssidewise movement of said clamping member, and which clamping member hasoppositely located openings through which a supply conductor may extend;and a screw carried by said clamping member and arranged at right anglesto said electrode; said insulating member having a recess adjacent theinner end of said screw whereby a short length of said electrode isexposed, and whereby a transversely extending supply conductor extendingthrough the oppositely disposed openings aforesaid may be forced intoengagement with said electrode by the inner end of said screw.

3. In a glow plug of the class described, an insulating member adaptedto be held in place within a passage in a cylinder wall, and whichmember has two longitudinally extending passages; electrodes locatedwithin said passages and whereby current is supplied to an ignitingelement at the inner end of the plug; clamping members supported by andlocated adjacent the upper end of said insulating member and wherebysaid upper end provides an abutment which restrains sidewise movementsof said clamping members, and which clamping members extend opposite toone another relative'to the axis of the plug; and screws carried by saidclamping members and arranged at right angles to said electrodes; saidinsulating member having oppo sitely disposed recesses adjacent theinner ends or" said screws whereby short lengths of said electrodes areexposed, and whereby parallel transversely extending supply Vconductorsmay be forced into engagement with said electrodesby the inner ends ofsaid screws.

4. In a glow plug of the class described, a cylindrical insulatingmember having a lower shoulder for supporting said member within apassage in a cylinder wall,Y and an upper shoulder for holding saidmember in place within said passage; two electrodes extending throughpassages provided in said insulating member; an ignitingv elementconnected to the inner ends of said electrodes; a tubular gland nuthaving a holding ring secured in piace within its upper end, and throughwhich the upper end of said insulating member extends; a gasket restingupon the upper one of the shoul-v ders aforesaid; a dished washerarranged between said upper shoulder and said holding ring; and meansfor connecting supply conductors to the upper ends oi said electrodes. Y

5. In a glow plug of the class described, a cylindrical insulatingmember; two electrodes extend` ing through passages provided in saidmember, and which electrodes have enlarged lower lends fitting withinenlarged portions thereof adjacent the'lower ends of said-passages;cement materials disposed at the points where the enlarged lower and theupper portions of said electrodes merge with one another, and wherebygas-tight joints are provided between said electrodes and the passagesthrough which they extend; means for holding said insulating member inplace within a passagev in a cylinder wall; Yan igniting elementconnected to the inner ends of said electrodes; and means for connectingsupply conductors to the upper ends of said electrodes. t Y

HECTOR RABEZZANA.

